4o had some notable problems with sycophancy being very very positive about the user and going along with almost anything the user said. OpenAI even talked about it [0] and the new responses to people trying to continue their former 'relationship' does tend towards being 'harsh' [1] especially if you were a person actually thinking of the bot as a kind of person.

[0] https://openai.com/index/sycophancy-in-gpt-4o/

[1] https://www.reddit.com/r/MyBoyfriendIsAI/comments/1qx3jux/wh...